Rebuild kit part# used: BK416WS. It is available on Cobra Transmissions site:
https://cobratransmission.com/nv-1500-synchro-bearing-gasket-and-seal-kit-50106006-1, for around $160 (April 2020), but I found the kit with same part number for about $110 on an Ebay listing. Other sources are available.
